Make CSSParserContext be garbage collected.

third_party/WebKit/Source/core/dom/SelectorQuery.cpp

 /*
  * Copyright (C) 2011, 2013 Apple Inc. All rights reserved.
  * Copyright (C) 2014 Samsung Electronics. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  *
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
@@ skipping 607 matching lines @@
 
 SelectorQuery* SelectorQueryCache::add(const AtomicString& selectors,
                                        const Document& document,
                                        ExceptionState& exceptionState) {
   HashMap<AtomicString, std::unique_ptr<SelectorQuery>>::iterator it =
       m_entries.find(selectors);
   if (it != m_entries.end())
     return it->value.get();
 
   CSSSelectorList selectorList = CSSParser::parseSelector(
-      CSSParserContext(document, nullptr, KURL(), emptyString(),
-                       CSSParserContext::StaticProfile),
+      CSSParserContext::create(document, KURL(), emptyString(),
+                               CSSParserContext::StaticProfile),
       nullptr, selectors);
 
   if (!selectorList.first()) {
     exceptionState.throwDOMException(
         SyntaxError, "'" + selectors + "' is not a valid selector.");
     return nullptr;
   }
 
   const unsigned maximumSelectorQueryCacheSize = 256;
   if (m_entries.size() == maximumSelectorQueryCacheSize)
     m_entries.remove(m_entries.begin());
 
   return m_entries.add(selectors, SelectorQuery::adopt(std::move(selectorList)))
       .storedValue->value.get();
 }
 
 void SelectorQueryCache::invalidate() {
   m_entries.clear();
 }
 
 }  // namespace blink